The Collaborative International Dictionary of English v.0.48:

Discipline \Dis"ci*pline\, v. t. [imp. & p. p. Disciplined; p.
   pr. & vb. n. Disciplining.] [Cf. LL. disciplinarian to
   flog, fr. L. disciplina discipline, and F. discipliner to
   discipline.]
   1. To educate; to develop by instruction and exercise; to
      train.
      [1913 Webster]

   2. To accustom to regular and systematic action; to bring
      under control so as to act systematically; to train to act
      together under orders; to teach subordination to; to form
      a habit of obedience in; to drill.
      [1913 Webster]

            Ill armed, and worse disciplined.     --Clarendon.
      [1913 Webster]

            His mind . . . imperfectly disciplined by nature.
                                                  --Macaulay.
      [1913 Webster]

   3. To improve by corrective and penal methods; to chastise;
      to correct.
      [1913 Webster]

            Has he disciplined Aufidius soundly?  --Shak.
      [1913 Webster]

   4. To inflict ecclesiastical censures and penalties upon.

   Syn: To train; form; teach; instruct; bring up; regulate;
        correct; chasten; chastise; punish.
        [1913 Webster]

WordNet (r) 3.0 (2006):

disciplined
    adj 1: obeying the rules
    2: trained mentally or physically by instruction or exercise;
       "the beautiful coordination of his disciplined muscles"; "a
       disciplined mind"

Moby Thesaurus II by Grady Ward, 1.0:

37 Moby Thesaurus words for "disciplined":
   Spartan, accepting, armed with patience, bound, bounded,
   conditioned, confined, copyrighted, cramped, endurant, enduring,
   finite, forbearing, indulgent, lenient, limited, long-suffering,
   longanimous, moderated, narrow, patented, patient, patient as Job,
   persevering, philosophical, prescribed, proscribed, qualified,
   restricted, self-controlled, stoic, strait, straitened, tolerant,
   tolerating, tolerative, understanding